


UTSM (Undertale + Super Mario)

by WillNewbie



Category: Super Mario & Related Fandoms, Super Mario Galaxy, Undertale (Video Game)
Genre: Crossover, Gen
Language: English
Status: In-Progress
Published: 2020-04-02
Updated: 2020-06-02
Packaged: 2021-02-28 17:00:56
Rating: Teen And Up Audiences
Warnings: Major Character Death
Chapters: 16
Words: 7,529
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23440588
Author URL: https://archiveofourown.org/users/WillNewbie/pseuds/WillNewbie
Summary: A mashup of Undertale and The Super Mario series.Long ago, there existed two races, humans and monsters. You know the rest, war and misery, blah blah blah, and now we're here. A child of Kindness faces familiar characters in a different, although still familiar, environment.The same goes for this. I'm leaving this up as a bit of an artifact of sorts.
Comments: 1
Kudos: 9





	1. Flamey

**Author's Note:**

  * Inspired by [Undertoad](https://archiveofourown.org/external_works/576793) by Lucas Pucas. 

**Summary for the Chapter:**

> A child falls.

**Notes for the Chapter:**

> Welcome to my first written work! Don't expect a masterpiece, now. I hope you enjoy!

A lone girl lies in a bed of multicolored flowers. Her pale hair and light blue dress lay splayed across the dirt. And yet, even after such a long fall, still she clutches her little gray pillow. It's shaped like a round star.  
Her blue eyes shoot open, and she awakens, scared. She looks around, clutching her pillow, in a new place all alone. She stands, her back aching, but appears fine. She is in a dark cave, light shining from a hole in the ceiling. This must have been where she fell. There's nowhere to go but a dark hallway to the right.  
She reluctantly goes down the passage, fearing the dark, but at a loss for alternatives. There's a doorway carved into the cave wall.  
Wishing there was another option, she heads into the darkness.

Another light shines from above onto a small patch of grass. The girl approaches tentatively. Then, out pops a small, red flower. The girl is shocked to see it has a face! Two lines for eyes, and a little smile.  
Then, it speaks: "Heya! I'm Flamey, Flamey the Fire Flower!" Flamey smiles invitingly. It's just a flower. The girl relaxes a little. He speaks again, "Hmm... You're new to the Underground, aren't you? Geez, you must be so confused! Someone aughta teach you how things work around here!" He winks, but he's eyeing the girl's pillow. "I guess I will just have to do," he says, still staring at the pillow. He has a weird look in his eyes, a strange shine. The girl holds it tighter, suddenly afraid. "Ready? Here we go!"  
Fire suddenly erupts around her! She looks around frantically for an escape, but can see none. She cries for help, but nobody comes. She looks back at Flamey. His face has contorted itself into a demonic smile, and she screams. "You IDIOT," Flamey says, his voice gravelly and sinister. "In this world, it's KILL or BE KILLED! Who in their right mind would pass up an opportunity this good?!" For a flower, he seemed to hold a commanding aura. Almost as if he was a mile above her. "Now. DIE." And the flames slowly close in on the girl. She cowers, tears streaking her face, her life over when it had barely begun. Still a child.

The clacking of heels echoes around the cave walls as a figure rushes to the screams of a small child.


	2. The Ruins

**Summary for the Chapter:**

> Somebody rushes to the aid of a child in need.

The fire comes closer, and closer, sweat beads forming on her forhead.. But a small heart with an angry face blinks into existence to the left of Flamey. It flies into him, uprooting him and sending him flying as he cries out. A tall woman in a pink dress now stands in his place.  
"What a horrible creature, always causing trouble for me and my subjects, and even torturing such an adorable little child!" The woman bends forward to the girl's level. "Now, who might you be?" The girl steps back, heart still racing after her brush with death. Everything was moving so fast... "Oh, I'm sorry. Do not be afraid. I won't hurt you!" The child stares at the floor, but steps a little closer. She mumbles something really quietly. "So, your name's Rosalina? That's a very pretty name! My name is Peach, Princess of the Mushroom Kingdom!" She holds out her hand. "Come with me. I can give you shelter!" The girl slowly reaches out her hand, grasping Peaches hand. Smiling, Peach takes Rosalina to the next room.

In the next room, the walls and floor are made of pink bricks. Brown, fuzzy leaves litter the floor, and green vines cover the walls. Stairs lead up to a pavilion where Peach is waiting. Something about this room stirs a strange new feeling. Strangely, it almost seems to come from her surroundings. A little unnerved, she clutches her pillow for security.  
The princess calls down from the pavilion, snapping Rosalina out of her thoughts, "Come here, child! We must continue, it's not safe to stay out here too long!" She squeezes her pillow one more time and runs up the stairs. She decides to leave those strange thoughts behind for now.  
Rosalina and the princess come upon a closed door in the following room. There are six buttons in the ground, two along a path and two more on each side. Peach presses each of the buttons not on the path and pulls a lever, and the door rumbles open. "This is a puzzle. Please, get used to seeing them, as there are many leftover throughout the kingdom," the princess says. Rosalina only nods.

In this room, there is nothing but a beat-up old scarecrow. Rosalina looks at it curiously. "Now, I must prepare you for the dangers of the Ruins," Peach says. "If you ever meet a monster, you will probably enter a Fight. If this happens, strike up a conversation." She gestures to the scarecrow. "Try it!" Rosalina looks at the scarecrow. She opens her mouth to say something, but nothing comes out. Summoning up every ounce of courage she has, she attempts to say something, anything! Instead, she looks away, ashamed. "Aww, it's okay," Peach says, laying her hand on Rosalina's shoulder. "That's fine, too! If you encounter a monster, just wait for me to come and get you." They leave, Rosalina's cheeks turning bright red.  
Here, there is an odd path on the floor, and a passage off to the right. "There is another puzzle in this room," Peach says. "I wonder if you can solve it?" She pats Rosalina's head and goes down the path.  
There is a sign next to the path, reading, "This room is the blueprint for the next room." Rosalina looks around. She feels... watched. Seeing nothing, she goes to be with Peach.


	3. Lumus

**Summary for the Chapter:**

> Something's watching...

Rosalina hears a sound behind her, and quickly turns around, starting to feel worried. Good thing she did, too, for something large and brown launches at her! She cries out in fear, grabbing Peach's attention. Unable to get out of the way, Rosalina just throws her pillow at it, bouncing off ineffectively. Peach, hearing her cries, panics, and runs towards Rosalina. The creature is a Goomba, a brown, mushroom shaped creature with feet and two fangs poking out of its mouth. It jumps in the air, preparing to land head-first into Rosalina.  
A green glow begins to emanate from Rosalina, and a little green heart appears before her. The heart stays suspended for less than a second, then flies into the pillow on the ground. It shoots from the ground, and slams into the creature! Two little eyes stare the creature down, lying on the floor. The Goomba doesn't understand what's going on, but is intimidated anyway. It slowly backs away, then turns around and runs off.  
Peach and Rosalina stand there, dumbfounded. The little star floats down to Rosalina. "Hi! My name is Lumus!" he says, despite not having a mouth. Peach cautiosly steps closer. "You're... alive?" she asks. "How?" The star looks over at Peach. "I don't really know, to be honest," he says, sounding slightly embarrassed. But he perks up a little, "But I think we share a soul, now! I can hear her thoughts and stuff too!" Rosalina looks a little alarmed at this. Isn't that a bit of a breach in privacy...? "But I'm strong, so I think I know why I'm here!" he says. He look down to Rosalina, still reeling from her pillow being able to talk. "I think I'm supposed to protect you!" he says. That catches her attention. "Would you like that?" he asks her. After being attacked out of nowhere, a pillowy bodyguard doesn't sound like that bad of a deal. She says yes in her head as a test. "Yay!" He exclaims, seeming to prove the experiment successful. "I promise I'll make sure no one can get close to you! He then flies back into Rosalina's arms, causing her to stumble a little.  
Peach looks behind her, looking to be in deep thought. There's a large bridge over water covered by spikes. She feels something stirring inside her, a motherly instinct beginning to kick in, and looks back at Rosalina and Lumus, seeming to have made a decision. "Perhaps... Puzzles seem a bit too challenging for now. Take my hand," she says, extending her hand to Rosalina. She takes it, and they walk on a path memorized by Peach after years of wandering these halls. Alone.  
The little hand holding hers so tightly reminds her of easier times.

**Notes for the Chapter:**

> Aaaaand here's an original character. Nice.


	4. An Unreasonably Long Hallway

**Summary for the Chapter:**

> Approaching a long, empty hallway, our friends think on recent events.

The next room is a really long hallway, and will probably take some time to get to the end. So, the two walk onwards in silence, all lost in thought.  
Rosalina thinks about her falling, the attack from Flamey, Lumus, and the strange woman she's been traveling with. So much to happen to a child in such a short amount of. However, her thoughts are then interrupted by those of another: Lumus. 'You don't like to talk much, do you?' he asks. Rosalina, still uncomfortable with the whole ordeal, thinks this is rather obvious. 'Well, I could also ask some questions, if you'd like! Assuming you'd be too shy, of course." That sounds okay. 'Great!' Lumus flies out of Rosalina's hands and next to Peach, "Hello!" Peach is startled out of her thoughts. "Oh, hello there, um, Lumus! What is it?" Peach asks with a smile. Something about it seems a little... off. "Well, we'd like to ask a few questions, if that's alright," Lumus answers. "A few...?" Peach says, seemingly worried about something. "Okay. A few shouldn't hurt."  
"Alright!" Lumus says, doing a little dance in the air. "First up, why does everyone want to hurt us?" Peach looks thoughtful, as if wondering how to answer. "They were told to. Their king... doesn't like humans," she says. "Why?" Lumus asks. Peach doesn't seem to want to say, but says, "Because humans pushed him and his people underground." Rosalina asks Lumus not to push the subject anymore. So, instead he says, "Well, where are we going?" Peach seems relieved at the change in subject. "We are going to my castle! After all, every princess needs a castle," she says, seeming to brighten up a little more.  
"Wow! Really?" Lumus says. Peach gives a small laugh. "Yes. It's really big, far too big for me," she says. Again, she looks sad for a moment, but it goes away quickly. "There's plenty of rooms to explore, and you can play with the Toads!" Lumus looks a little confused, "Play with frogs?" Peach laughs again. "No, silly. They're a nice race of monster that only want to help me," she says. "They followed me when I first came her. They consider me their queen, but I just prefer princess."  
Peach forward, away from Lumus, and sees that they're reaching the end of the hallway. "Well, that's enough talking for now," Peach says. She gets down to come face to face with Rosalina. "I want you to stay here, okay? I'm going to go, and prepare a surprise," she says. Rosalina nods, slowly. Peach smiles. "Okay. Remember, don't leave this room. Other monsters may try to hurt you out there," she says, a serious look in her eye. Rosalina nods a little faster this time. "Okay. And, here," she hands Rosalina an old phone. "Call me if you need anything, my number is already on there. I'll see you in a little bit, okay?" And with that, she gets up and leaves, waving goodbye behind her. Lumus waves back, and Rosalina raises her hand a little and waves.


	5. Daring

**Summary for the Chapter:**

> Rosalina thinks. Lumus whines.

"It's been so long. When is she coming back?" Lumus says from the ground. Rosalina's sitting in a corner, thinking. Lumus knows what she's thinking about. 'Hey.' Rosalina jumps, still not used to the invasion of privacy. 'I'm not invading anything! I'm a part of you, remember? Your thoughts are mine. Rosalina just nods. She looks so sad, Lumus can't put up with it. "Okay, that's it!" he says out loud. "We're leaving!" She doesn't understand, they're supposed to stay and wait. Maybe try calling her again? "No, we tried that already. She just says she's busy. Well, we're not, and we can't stay here forever," Lumus says with finality. Rosalina reluctantly agrees. At least it'd distract her from her thoughts.  
"Good!" He says, and they head out.  
In the next room, there's doors to the left and right. More leaves litter the floor. To the right is a room with a candy bowl, with a sign next to it saying: "Please take one." Rosalina obliges. As she heads back into the room, her phone rings, giving her quite the scare. As Lumus recovers himself, Rosalina answers. "Hello! It's me, Peach! I hope you're staying in that room! There are a few puzzles up ahead, and I wouldn't want you to hurt yourself. So stay good, okay?" She hangs up. Lumus floats up back up. "She doesn't need to be so protective. We can handle ourselves, you know!" He goes back to Rosalina's hands, and they head for the door.  
However, Rosalina gets a little distracted by the leaf piles. Unable to help herself, she steps through, feeling them crunch satisfyingly beneath her feet. Under the pile however, is a little white ball. Then, it floats into the air. It has a face! "Eek!" It says, blushing. It covers it's face, hoping that they'll go away. Rosalina attempts to approach it to ask what's wrong, but it just cries out and flies through the wall. "What was that about?" Lumus says. Rosalina just shrugs, and they head out.

The next few rooms would be quite boring to describe, and would honestly only serve as useless filler, so I think I'll just skip to the important bits.

A bit worse for wear from encountering creepy carrots and crazy caterpillars, Lumus and Rosalina arrive in a room with, surprise surprise, leaves littering the ground. However, there's another boo lying on them, and he's blocking the way. Rosalina approaches him, prodding him with a stick. "ZZZZZZZZZZZZZZZZZZZ" is all he says. "Does it thinks it's a bee or something?" Lumus asks. "It's just saying "Z" over and over again..."  
*Move it with force?  
💚Yes-----------------No

**Notes for the Chapter:**

> OKAY. The initial story dump is over, probably best to say this: I'm not some acclaimed author. I'm learning, though. So, ifyou have any critiques, then I'll happily listen. Just don't be a douche, alright? Thanks! I'll keep working, and put out another chapter soon. If anyone even reads this...


	6. Napstaboo

**Summary for the Chapter:**

> A new foe approaches! ...Reluctantly.

The boo's eyes blink open, and it slowly rises off the ground. It turns around, and, seeing an audience, screams. It would appear he's even more shy than the typical boo. So, he fades away.  
"Hey! Where'd he go?" Lumus says. He and Rosalina twist around, and there he is, right behind them. It looks like he was trying to get close, but when they look at him, he just shrieks again and fades.  
"Oh, don't be like that! We won't hurt you!" Lumus calls out. "We just want to be friends!" "Friends?" says a timid voice from above. Before Rosalina has the chance to look up, a drop of water hits her head. The water is filled with such a deep fear, she immediately cowers with her hands over her head. -3 HP  
Lumus shoots above Rosalina's head. "What was that for?!" he cries. More drop onto Lumus, not affecting him. With a clear view of the ghost, he then has a horrific realisation.  
"I- is this drool?!" he yells. Napstaboo looks down in horror, realising what was going on. Then he sees Lumus looking at him, and fades again. To their left, he says, "Y- yes... It's just a condition some boos have, considering how little we close our mouths... I'm so sorry...." Rosalina and Lumus silently agree to keep their backs to him. "Well... Why are you so shy?" Lumus asks. "It's just us boos... We don't like to be seen... But... I..." And he stops. Rosalina turns around curiously.  
His head (body?) is turned to the ground. Drops hit the ground, though it's hard to tell if they're tears or saliva. Rosalina kneels down and makes eye contact, giving a reassuring smile. He looks terrified for a second, but something changes. Rosalina's soul glows green again, and something unseen passes between the two. 

With everyone calmed down, Napstaboo sniffles and looks just below Rosalina's eyes. "Usually, I come to the Ruins to be alone... Instead, I met someone nice..." Rosalina smiles, happy she could help. Lumus just bobs in the air and smiles with his eyes. "Oh, am I in your way... I'll go..." And with that, he fades away.  
"Hm. He was shyer than the average boo. Wonder what happened..." Lumus ponders. Rosalina can only shrug. And so, with thoughts of wonder in their heads, the two continue on their way.

**Notes for the Chapter:**

> Welp, finally got around to making another chapter. Locked up in quart, my life's only gotten busier and more stressful. But, I just sat down finally and did it.


	7. Spider Bake Sale

**Summary for the Chapter:**

> A small chapter to describe a small visit to a small bake sale.

Our daring duo decide to head straight through the door at the end. The next room, however, is completely empty. However, as Rosalina turns to leave, Lumus stops her. "Hey, there's some spiderwebs over here," he says. Why should they care about some gross spiderwebs? Well, as it turns out, there's a flier in one, reading, "Spider Bake Sale! All proceeds go to REAL spiders! (And witches)"   
"A bake sale?" Lumus says eagerly. "We've gotten some pocket change, right?" Rosalina nods. Some of the monsters they've encountered gave them some money for their kindness. "Alright then!" Lumus didn't need to be told twice, immediately heading for the webs. Two other webs have pages in them, reading, "Spider Donut- 7G" and "Spider Cider- 18G". They could only afford a donut, so Rosalina tosses seven gold in the web. A little spider crawls out, somehow carrying an entire donut on its back.   
They leave, Lumus calling back, "Thank you!" as they walk out.  
Outside the room, Rosalina inspects the donut, only to find some... odd appendages poking out the sides. Rosalina and Lumus exchange a look, coming to a silent agreement (to us) to only use it as a last resort.

**Notes for the Chapter:**

> HEY, IT'S MIDNIGHT, BUT SCREW, I'M NOT GETTING ANY WORK DONE, SO HERE WE ARE. Just a small one here. Probably gonna put out the next chapter as well pretty soon.


	8. The Mushroom Kingdom

**Summary for the Chapter:**

> Rosalina, Lumus, and Peach finally reunite. Together, they enter The Mushroom Kingdom.

After braving more puzzles and befriending more monsters, Rosalina and Lumus come across a large tree in the middle of a hallway. They say this tree's leaves have magical properties. But, only if freshly picked. But any time this old tree grows any leaves, they fall right off. Large, brown leaves surround it. Seeing this poor tree, powerful, but restrained, fills her with Kindness.   
The steady clacking of approaching heels bounce off the walls. A voice can be heard from behind the tree, "Oh, I hope they are okay. That took much longer than I expect..." Suddenly, Rosalina's phone rings. Princess Peach appears from behind the tree, startled at the sudden noise.   
She's being escorted by two little men who appear to be wearing large, round hats with blue spots on them, and are clothed in tiny blue armor. They're holding spears, and, seeing Rosalina, ready their weapons against the stranger. Lumus jumps from her hands and hovers in front to protect her.  
"Rosalina!" Peach calls out. Ignoring the protests of her escorts, she rushes to the child and cups her cheek in her hand. "Oh my, are you hurt?" Then she remembers. "Didn't I tell you to stay in that room?" she scolds. Rosalina blushes deep red. Peach smiles, and wraps her hands around the child. "It's okay, as long as you're fine!"   
Peach stands and turns towards Lumus and her escorts, who are currently in a standoff. She laughs. "Oh, quit it you three! We're fine," she says, moving between them. "Rosalina, Lumus, these are the Toads. They are two of my royal guard!" she says, gesturing to the little men. The Toads hear her words, and realisation dawns on their faces. One shoots into a rigid posture, saluting, shouting, " Forgive me! I was not aware that these were the guests you were speaking of!" The other Toad looks at his partner. "Calm down, 27. You don't need to be so serious all the time," he says. The saluting one, 27 apparently, turns to his comrade enraged. He then proceeds to chew him out for several minutes while everybody walks to the end of the hallway.  
Lumus and Rosalina seem a little bothered by something. "Peach?" Lumus asks. "Did that Toad call the other one '27'?" Peach giggles. "Yes, he did. The reason is the Toads aren't big on names. They prefer to just go by numbers, with a few exceptions." Lumus goes back to Rosalina's arms, still a little confused. Why would someone not want a name?  
At the end of the hallway, there is a large archway. Past it is a rather large cavern, full of mushroom-shaped houses, with a large white-and-red castle in the back. "Welcome," Peach says. "To the Mushroom Kingdom!" Lumus and Rosalina sit and take it all in. It's pretty small for a kingdom, but Peach seems proud anyways.   
They head down a staircase into the cavern, the Toad escort 27 still bickering with his partner, named 16, as gathered from the argument. The group walks down the streets passing many houses and through a market. There are many Toads running about their business, but stop and save when they see Princess Peach passing bye. Each wave she returns, absolutely beaming until the end. Rosalina, after the general quiet of the Ruins, feels quite overwhelmed, and just buries her face in Lumus, who doesn't mind.  
At last, they arrive at the bridge into the castle. The castle is completely built from white brick, and the roof is made from red tiles. Above the entryway is a large stained-glass window of Princess Peach holding her hands out, with a red heart floating above her palms. It appears to be a soul.  
27 finally calms down once the approach the door. Though it would appear that he has more to say, but he'll save it for when the Princesses aren't around. 16 just can't wait for break.  
Peach stands in front of the large oak door excitedly. "Rosalina, welcome to your new home!" she says ecstatically. She then pushes the door open.

**Notes for the Chapter:**

> I should probably stop here...


	9. Home

**Summary for the Chapter:**

> After a long trek through the Ruins, Rosalina and Lumus finally find peace and shelter.

Inside the castle is a large, circular chamber. The walls and floors are white, and the red ceiling goes into a cone. Two staircases leading up to a platform, on which a throne lay. In the center of the room, the floor dipped down into an image of the sun. In front of this, underneath the platform, was a door with a large yellow star on it. Red carpeting went up the stairs, around the sun, and down two passages to the left and right.  
Rosalina steps onto the sun, looking around her, taking it in. It is certainly different from what she is used to. It was like something out of a fairytale.   
Peach then interrupts their stupor, saying, "Welcome to your new home!" Rosalina starts at that. A new home? But she doesn't get much of a chance to think about it, as Peach begins directing her to the passage to the right. They stop at the first door in this hallway. "This will be your new bedroom!" Peach says excitedly. New room? Again, peach loses her train of thought as Peach lays her hand on Peach's head. The feeling she's getting from this woman... It's something so familiar. Peach suddenly takes her hand off Rosalina's head and covers her mouth. "I need to go, really quickly! I'm sorry, make yourself at home!" and she runs off.  
"Did you feel that, too?" Lumus asks. Rosalina just nods.   
After wasting enough time standing outside, doing nothing, the two enter their new room. It's actually surprisingly small. Hardwood floors, a little bed in the corner, a wardrobe, a shelf, and a lamp on a lampstand. It was strangely normal.  
Looking at the bed, Lumus and Rosalina finally realise how exhausting their journey had been so far. Hesitant at first, they approach it, until just completely falling over onto the covers. Without even bothering to cover up, they fall asleep. 

They wake up some time later to find the light off. Rosalina gets off the bed and turns on the lights, Lumus still sitting on the bed. (As much as a sentient star pillow can sit) He floats off the bed to the middle of the room, where a slice of cake lies on the floor. "Where'd this come from?" Lumus asks. Rosalina just shrugs, and picks up the plate.   
A sharp knock on the door makes them both jump, Rosalina frantically trying to regain balance and not drop the cake, and Lumus falling on the floor. The door opens, and 16 walks in. Seeing the looks on their faces, he starts apologizing. "I'm sorry, did I scare you?" he says, smiling awkwardly. "I'm sorry, but Princess Peach told to escort you once you woke up." Lumus gets off the floor, and Rosalina goes outside with the Toad.  
"The princess says she wants to see you in the library," 16 says as they walk into the hall. He leads them on, and they start through the halls in silence. Rosalina observes the many doors they pass, each one with a sign saying, "Under Renovation" and boards over them. Why have so many rooms and not allow access to any of them?

**Notes for the Chapter:**

> WHOOO. How long has it been? I dunno, it's late, and I'm not gonna check. But this is LONG overdue. I have a few reasons why I haven't been updating, so, if you want, you can skip this. Just figured I aughta explain myself.  
> So, I'm a new author. This is my first attempt at a full work and not some short thing, so it's big. But that comes with the issue of inexperience. So, I'm not Rick Riordan yet. But I can't help but think that my writing style is, well... Boring. It may just be me, but that's how I feel. So, I'd get in my own head, and it'd make me wanna stop.  
> Schoolwork. 'Nuff said.  
> Laziness. 'Nuff said.  
> Also, this was actually finished a while ago without me even realizing it. Turns out, where I left off was a great stopping point, adding more just made it feel too long.  
> So, yeah. I'm BACK baby, and I'm motivated! God, please lemme keep this! GOODNIGHT! And Amen.


	10. The Library

**Summary for the Chapter:**

> Rosalina and Lumus enter the castle library, a massive room filled with books. But it seems like Princess Peach is hiding something.

After some time, they come across a large oak door at the end of a hallway. Entering, they come into a massive room, with all the walls covered in books. Rosalina stares up in astonishment, absolutely in awe. (Nerd) In the center of the right wall is a large fireplace. In front of the fire are two massive armchairs, with Princess Peach sitting in one, reading. The chair almost makes her seem tiny.  
Looking up, Peach beams at the three. "Like what you see?" she says. Clearly, she's very proud of it. Rosalina just stares around her, completely overwhelmed. Lumus looks equally in shock. "I've never seen so many books!" he says. 16 seems a little confused by this. "How many books have you seen? You just came to life, right?" Lumus slowly moves his eyes from all the books to 16, and says, "I share all of Rosalina's thoughts and memories. Whatever she's seen, I've seen, too!"  
Peach sets her book down and goes to hug Rosalina, but notices she's still holding the cake. "Oh, were you not hungry?" Peach asks. Rosalina shakes her head. "Oh, well in that case," she says as she picks something up off of a nearby table. "Put it in here!" She's holding out... a small leather purse... Rosalina just looks confused. Peach, seeing this, realizes her mistake. "Oh! I'm sorry, I forgot. It's magic! You can put anything in it!" she says. Then she picks up 16 by the hat(?). "Hey, hey, HEY! What gives, princess?!" he cries out, thrashing his arms wildly. She doesn't listen, and instead, thrusts him into the bag. He completely fits, and there's not even a bulge of any kind. Though, it does seem to get slightly fuller.  
"See?" Peach says triumphantly. She then reaches back in (all the way up to her elbow) and pulls him back out. He doesn't look thrilled. "Hey, don't give me that look!" Peach tells him. 16 just glares. "Well, excuuuuse me, princess, if I'm not that big of a fan of getting stuck in a bag!" he references. Rosalina and Lumus giggle, Peach joining in. Even 16 lets out a nervous chuckle.  
Done laughing, Peach gets back on topic, holding the bag out. "It can hold up to eight objects of any size," she explains. Rosalina takes the bag and puts it on. Peach looks extremely pleased with herself. Content, she picks her book up and sits back in her chair. "Feel free to wander the library as you wish. You can read anything you want, just don't leave the room. I wouldn't want you to get lost!" she says. She returns to reading, and 16 leaves the room.  
Rosalina and Lumus look around, exploring the massive shelves. She felt so lost and so small, it was pretty overwhelming. How could she possibly pick one book out out of millions?  
After looking around for some time and having no luck whatsoever, they decide to return to Peach. They figured it was time to go anyways, and they didn't want to be too much of a burden.  
Peach still remains in her chair reading the same book. The title reads, "75 Uses for Cake." Peach, noticing them approaching, says, "Oh, so you want to chat? That's okay! Why don't you have a seat?" She gestures towards the other massive chair. Taking a seat, Rosalina feels even smaller than before. "So, what did you want to talk about?" Peach asks.  
Rosalina and Lumus look a little uncomfortable. Lumus of course speaks, "Well... We were wondering when we should go home?" Peach looks a little startled, and her eyes widen a little. What's she so afraid of? "U-Um, well, you see... I can't really do that..." Peach says. She's noticably uncomfortable. "But, that doesn't matter! Besides, there's so much for us to do here! I could show you my favorite flower picking spot, I could teach you to cook, I could even give you lessons! There's plenty information in here, so it shouldn't be that hard!" She speeds through her words, almost seeming a little desperate. Lumus looks confused. "Why not? How do we leave?" he questions.  
Suddenly, she slams her book shut, scaring Rosalina and Lumus. "I... have somewhere I need to be," she says, and she runs out the door. What was all that about? Rosalina and Lumus get up, deciding to find out.

**Notes for the Chapter:**

> Oooohohoho. It's about to get good.


	11. Determined

**Summary for the Chapter:**

> Peach is acting strange.

Cautiously passing through familiar corridors, Rosalina and Lumus at last arrive in the main hall. They watch as Peach hurriedly enters the large star door, slamming it behind her.  
"What the heck is she doing?" Lumus wonders aloud. But, he didn't really need to, since Rosalina was thinking the exact same thing. Hesitantly, she goes up to the door. Princess Peach is acting really weird, and Rosalina's really worried. So, coming to a decision, she opens the door.  
A spiral staircase leads into a completely different castle. The walls are no longer a pristine white, or even a slight pink, but a dark grey. Torches line the walls, and there's a face that repeats in between them. A monster with horns and a large, gaping mouth with two sharp teeth. It's much different down here than the friendly and inviting atmosphere of above.  
At the bottom of the stairs, Princess Peach has slowed down, moving at a steady pace down the dank hallway. Rosalina and Lumus quietly follow, until she stops.  
She sighs. "You want to go home right?" She stares straight ahead. "Up ahead is the exit from the Ruins. A one-way door to the rest of the Underground. I'm going to destroy it. So please, go back upstairs." And she continues forward. Rosalina and Lumus exchange glances, and continue to follow.  
She stops again. "Every human that has fallen down here has met the same fate. They have their souls stolen. Myself included." Her soul... stolen? Who, and how? Why? But this shocking news does deter them. It only makes them more... something. So they follow her around a corner.  
She stops again. "So naive... If you leave the Ruins... They... BOWSER... will take your soul, too. And if he doesn't enslave you, he will kill you. I am only protecting you!" She stops. She's lowers head and puts her hand to her face. She's hiding her tears. Raising her head again, she says, "Go upstairs. I will not repeat myself." And she continues onward.  
Rosalina and Lumus continue as well.  
The hallway opens up into a larger room. At the end of it is a large door, bearing a large version of the creepy face from the hallways. Vines tangle the walls, twisting between the bricks.  
Peach stands in front of the door. "You really want to leave that badly, huh? Hmph. You remind me of someone. Very well then." Quickly she turns around to face Rosalina and Lumus. Her eyes stare down at them coldly. "The only solution would be for me to fight you! Prove to me that you are strong enough to survive!"

**Notes for the Chapter:**

> Prepare yourself for heartache.


	12. Princess Peach

**Summary for the Chapter:**

> Princess Peach blocks the way.

"I'm sorry, WHAT?!" Lumus yells. But Peach doesn't seem to hear him. Instead, she draws a closed parasol from behind her, seemingly out of thin air, and raises it above her head. Her face is completely emotionless.  
"This is for your own good," she says, and she brings her arm down.  
White hearts (with angry faces?) appear and fly towards Rosalina.  
Lumus throws himself through the air in front of her, taking every bullet for her. Neither of them are hurt. "This is crazy!" Lumus yells. Peach is acting aloof. "It doesn't matter. Human or Monster, fighting is a part of life," she says. Ironically, talking does not seem to be the solution to this situation. She sweeps her parasol, slicing through the air. More angry hearts appear where the parasol leaves, and they all launch at Rosalina.   
Rosalina helps guide Lumus with her mind, catching things he can't see. The battle continues on, the two moving in perfect unison. As for Peach, her movements are swift, smooth, and graceful. A trail of hearts fly from the tip of her parasol, creating intricate designs in the air. She glides around the battlefield to attack from all sides. Despite her previous talk of peace, she sure knows how to fight.  
This goes on for some time. Both sides know they're growing tired, but both are set on their goals. And the more Rosalina refuses to fight, the more frustrated Peach gets. Her face starts to reflect this as well, started to seem quite angry. Her attacks are faster, more forceful. Hearts fly from many directions as she seems to almost float through the air while attacking. Until finally, she's had enough.

More hearts. More dodging. Rosalina and Lumus have given up on talking. It's just a simple rhythm. Run, block, repeat. They have been slightly damaged, and the monster candy didn't do much. They were reluctant to eat the cake though, hoping to save it for another time. They pressed on anyways, desperately holding onto the hope that Peach will finally stop. Peach attacks from the right, Lumus immediately intercepting. Peach sweats, some of her grace being replaced by ferocity. Flying back to the north, she swings her parasol in a wavy pattern to hopefully throw them off. But they've seen this before. Landing in front of the door, she stops. She's out of breath, panting. Her right hand hangs low, her parasol dragging on the ground.  
"Are you finally done?" Lumus asks. Rosalina's sweating and out of breath, too, but, being a pillow, Lumus is mostly fine. But if Rosalina goes down, so will he. Peach is staring at the ground. "If you don't fight... you will be captured... and I don't want to think about what will happen then... " She looks up. "I... am not done..." And she smiles.   
Peach holds her parasol up again, and opens it. Hearts appear all around Rosalina and Lumus, trapping them. "Forgive me... This is mercy..." Peach says. Small tears start to form under her eyes. Then she closes the parasol.  
All the hearts come crashing down on Rosalina and Lumus.   
Peach drops the parasol.

**Notes for the Chapter:**

> 0_0


	13. Enough

**Summary for the Chapter:**

> Chara... No matter where you go, or the challenges you face... I hope that you remain Kind...

*Your HP was maxed out!

The dust clears. Confused, Rosalina and Lumus stand up, completely unharmed. Seems she couldn't do it.   
Peach drops to her knees. "Please. Just... go back." She's holding back tears. "I know how much you want to go home... But it's not safe..." Tears escape from her eyes. "I'll take good care of you..." Her tears splash the floor. "And there's so much to do and explore..." She hiccups, still trying to restrain herself. "You could truly have a good life here. You could make friends." A sob this time. "Please! Just... stop being so difficult..." More sobs. "How can I run an entire kingdom... If I can't even protect one single child..." She breaks down completely now, shuddering and sobbing uncontrollably.  
But what Rosalina can see only shadow. Darkness surrounds Peach, twisting and writhing, creating an inescapable prison. She can hear evil thoughts, like "Pathetic" "Worthless" "Failure" She doesn't know where this came from, and it's scaring her. But something makes her step forward. Looking at someone who cares about her so much hurting so much fills her soul with Kindness. So, she goes into the darkness.  
Just standing this close to her, she can feel the whirlwind of emotions. Guilt, shame, fear, so many feelings at once, it's no wonder she's so broken-down. It feels quite familiar.   
When Rosalina finally finds her, her head is in her hands, and she's sobbing. Rosalina gets onto her knees as well, and throws herself onto Peach, giving her a hug.  
All at once, the darkness dissipates. The swirling voices go silent. Light from torches on the wall shines through.  
Peach looks down in shock at the child embracing her. Her little arms reach as far around Peach's waist as she can. Once her shock subsides, Peach slowly returns her embrace. The two remain locked together for some time, allowing time to calm down. Lumus even latches onto her bakv, his tiny arms unable to go around her body in any way.  
After a time, Peach gently pushes Rosalina off of her, and Lumus lets go of her back. They all stand up (Or float up, in Lumus's case), dusting themselves off. When they're done with this, Peach looks Rosalina in her eyes.   
And she smiles.  
Rosalina thinks it's one of the most beautiful things she's seen in her life.   
"I understand," she says, finally breaking the silence. It wouldn't be best for you to grow up trapped down here, no matter how large my castle may be. In fact, it's quite small once you get used to it." She turns around and lays a hand on the door. She looks up at it, almost longingly. "The expectations of being a princess... The loneliness of being the only human around here... The fear that I can't protect the ones that look up to me... They took hold of me. And I'm sorry for that." She turns back to look Rosalina in the eyes. "I'm deeply sorry for that. And if you truly wish to leave, I have no right to try to stop you." She taps her parasol against the door, and it opens. "My only request is that you don't return. I hope you understand," she says.   
And she leaves. Just before leaving the room, she turns and looks back. Rosalina sees, and waves, along with Lumus. Peach waves back, and turns back and leaves.

**Notes for the Chapter:**

> Every good story needs a healthy dose of feels, and Undertale is perfect at that. I hope I did well at emulating it at least!


	14. See You Soon!

**Summary for the Chapter:**

> This guy again...

Past the door is darkness. The only light is from a hole high in the ceiling, shining down on a lone patch of grass. "I don't like this..." Lumus says, worriedly.  
Then he appears in a flash of fire, with his same cheery smirk. Flamey.  
"Heya! I see your back," he says. Rosalina doesn't let her guard down this time, Lumus preparing to create an opening if necessary. "What do you want?" he says. Flamey's face doesn't change. "Just figured I'd give you a friendly goodbye! I saw your battle with the Princess, truly exciting stuff!" His face doesn't change. "You didn't even have to kill her! Even though she was asking for it." His face starts to darken. Lumus moves in front of Rosalina. "How pathetic! She just wanted an easy way out! What a coward. And you?" His smirk grows. It spreads across his face, stretching beyond the limit. "You didn't even fight back! You're lucky your enemy was such a spineless coward," he says. That last remark sets them off. "You take that back!" Lumus cries as he launches himself at the little flower. It was in vain, however, because vines shoot from the ground and catch him in the air. Rosalina feels a slight tug, probably.from her soul.  
Flamey's cackles bounce off the cavern walls, almost making it seem like there's more of him. "See? I knew it, look what happens if I push hard enough!" He squeezes Lumus a little harder. "Look at you, completely at my mercy. What can the child of Kindness do without her guardian angel?" Rosalina starts forward, but stops. He's right. She can't do anything on her own. She's worthless.  
"Hahaha! Seems you agree. But, don't worry, I won't hurt you. Yet. This is much, MUCH more fun!" The vines retract, releasing Lumus. As flames erupt around Flamey to take him away, his face seems to extend and contort, his mouth growing massive. His teeth extend, and his mouth gapes open, letting out his chilling cackle before the flames overtake him.  
And with that, he's gone.  
"That guy is really creepy," Lumus remarks. Rosalina nods in agreement. So, they walk onwards, carefully avoiding the pile of ash that once was grass. The hallway continues onward for some time, growing brighter and brighter, until they come across another archway. This one, at the crest, bears the same face as on the walls.  
With one last look behind them, the duo head into the great unkown.

**Notes for the Chapter:**

> UNDERTALE + SUPER MARIO  
> by Shigeru Miyamoto  
> by Toby Fox  
> by Will Newbie


	15. Shadows in the Snow

**Summary for the Chapter:**

> Finally exiting the ruins, our heroes are met with a frozen forest. But it would appear the cold is the least of their worries...

The air outside the Ruins is frigid. Rosalina and Lumus are immediately met with icy winds when they step past the door. It slams shut behind them, stranding them in the cold.  
The world is blanketed in a sheet of white. Trees grow thickly together, barring any entry, and creating a path that only leads forward.  
"Umm... Are we on the surface?" Lumus asks. It's a valid question, considering there's snow and trees underground. Deciding they have no other choice, our heroes trudge onwards, determined to return home.  
The path goes on for some time. The only sounds are those of their footsteps, and the wind howling through the trees. It's eerie. A small log lays in the path, the only disturbance in the mostly same landscape. It's probably rotten, so Rosalina steps over it, not giving it a second thought.   
A loud SNAP comes from behind. Rosalina and Lumus whip around, already on edge. There's no one there. Just the log from before, but seemingly stepped on.  
Lumus seems to relax a little, saying, "It was probably some kind of animal. There's bound to be some in a forest, right?" He doesn't sound so sure.  
With nothing more to say or do, they move on, but noticeably more on edge. The silence returns.  
Until it's broken by the sound of other, heavier footsteps. A shadow appears in the corner of Rosalina's eye, and she turns to look at it.  
But there's nothing there. Not even any footprints.  
"J-Just an animal. That's all. We're fine. I-I'll protect you!" Lumus says. He doesn't sound very confident... But they press on anyways, moving much faster than before. Finally, they come across a bridge, and it looks as if the forest opens up on the other side. Though many boards are missing, making Rosalina wonder at it's structural integrity.  
But those footsteps return. And Rosalina can't move. Try as she might, she's stuck in place. Whether it's from fear, or some outside force, she's powerless against it. She hugs Lumus close to her chest as the steps come closer...  
And closer...  
And closer...

**Notes for the Chapter:**

> The moment you've all been waiting for. If any of you really have.


	16. First Contact

**Summary for the Chapter:**

> Something's creeping behind Rosalina... Perhaps this is one of the monsters Peach was talking about. What could he want?!

Breathing. That was the only thing Rosalina could do anymore. Her heart beats faster, her breath becomes shallow, sweet beads drop from her chin...  
The footsteps stop. They (or it) are right behind her. She can almost feel their breath on her neck. Until finally, they speak, slowly and deliberately...  
"Human... Don't-a you-a know... how ta greet... a new... pal..." His accent... Italian? "Turn around... and- a shake-a my hand..."   
She has no choice. She can't run away, and, if she did, there's no telling what this monster could do to her. So she does what she's told. Slowly, she turns around. Perhaps Peach had second thoughts? Maybe she's going to come crashing through that door and throw and angry heart at this thing.  
Or maybe not.  
Or maybe this thing will grab her hand and yank it off, devouring it before her eyes. This must be what Peach was talking about... The monsters out here are ferocious!  
All of these thoughts ran through her head in the time it took her to face the monster. She couldn't really see him, just his hand. Slowly, she reaches for his outstretched hand. Anything could happen to her now. Absolutely anything. Rosalina prepares for the worst.

*PBBBBBBBBBBBBTHHHHHHHHHHHHHHHHHHHHHHhhhhhhhhhhfffffu*  
But not that. Definitely not that.  
The monster pulls his hand away, laughing. And she finally gets a good look at him. It's not a monster at all in fact. It's a man. Wearing a green hoodie. "Haha! Tha 'ol whoopee-cushion-in-tha-hand trick. Never gets old." Rosalina just stares at him, trying to understand. Another human? She was expecting a monster, not this guy... A tall man with a large mustache stands before her, wearing a green hoodie decorated with a green "L" inside ea white circle.  
"You're a human, right? What a coincidence, I'm-a supposed ta be-a hunting humans right now, actually. Tha name's-a Luigi, by the way. Luigi the Former Plumber."

**Notes for the Chapter:**

> Hey, 100 hits! Pretty cool. Seems somebody does care! (It's only 99 right now, but it'll probably be 100 in the morning, at least) Well, thanks for reading! (If you even made it this far.) I think now would a good time to work on a side project. A Gardevoir's Loyalty, coming soon! (Unless I lose confidence again and quit) Also, he's here! Luigi is Sans confirmed!

**Author's Note:**

> DISCLAIMER: I am not affiliated with Undertoad. They were the initial inspiration for this AU, however I have not read it, nor do I intend to until the finish of this story to try to prevent it from looking like I stole anything.
> 
> Also, this work is NOT Super Mario. This story is going to be much darker. So, please, don't read this expecting something funny and light-hearted. There is a lot of moments dealing with death and grief. So, please, be warned.


End file.
